Dietary isoflavones and gastric cancer: A brief review of current studies

Although several in vitro and animal studies have suggested that isoflavones might exert inhibitory effects on gastric carcinogenesis, epidemiologic studies have reported inconclusive results in this field. The aim of this brief review was to investigate whether such an association exists among dietary isoflavones and gastric cancer incidence, prevention, and mortality in epidemiologic studies. We conducted a search of PubMed, Google Scholar, Cochrane, Science direct, and Iranian Scientific Databases including Scientific Information Database and IranMedex Database (up to November 2014) using common keywords for studies that focused on dietary isoflavones and gastric cancer risk. A total of nine epidemiologic studies consisting of five case-controls, three prospective cohorts, and one ecologic study were included in this review. An inverse association between dietary isoflavones and gastric cancer was shown in only one case-control and one ecologic study. In summary, whether anticarcinogenic properties of isoflavones are established, research found no substantial correlation in this field. There are insufficient studies to draw any firm conclusions about the relationship between isoflavones intake and the risk of gastric cancer. Hence, further evidence from cohort and trial studies are needed.